Fort St. Vrain
Platteville, Colo., United States
High Temperature Gas Cooled Reactor (HTGR)
Net Output: 330 MWe
Decommissioned. Date started: 01/1979.
Date closed : 08/1989.

The Fort St. Vrain Nuclear Generating Station, located near Platteville, Colorado (35 miles north of Denver), began life as a DOE demonstration plant in 1973. The original plant construction began in September, 1968, and the first electricity was generated in December, 1976. The 330-MWe (net) high-temperature, gas-cooled reactor (only one in the nation) was taken over by Public Service Company of Colorado in 1979 and run as a commercial entity. The reactor utilized helium gas, instead of water, to transfer the heat from the reactor core at about 1,400°F to produce steam. A converter reactor, it used U235 and Thorium as fuel. Thorium is non-fissionable and less costly than other nuclear fuels, but when combined with U235 it is converted into fissionable U235.

Public Service notified the NRC in 1988 that it had decided to halt Fort St. Vrain operations early because of high operating costs and the plant's frequent shutdowns. The plant operated during December 1976 and August 1989, in between a series of reactor shutdowns. Various reasons contributed to the shutdowns. In June 1984, the reactor was shut down because of moisture in the core. The plant was shut down again in May 1986, pending compliance with the Department of Energy's "Environmental Qualification" regulation. In July 1988, Fort St. Vrain was shut down for scheduled repairs. The plant was last shut down in August 1989 to repair a stuck control rod discovered during routine safety testing. During the repair activities, hairline cracks were discovered in tubes that supplied heated steam to drive the turbine. It was apparent that to continue operations would no longer be cost effective and Public Service Company decided to cease its nuclear operations at Fort St. Vrain. The plant only operated 15 percent of the time between 1979 and 1989. The company closed the reactor permanently the following year. It was the first long-term operating, commercial nuclear reactor in America to be decommissioned. Decommissioning was completed in 1996.

On August 5, 1997, the NRC terminated the operating license of the decommissioned plant, and released the site for unrestricted use, as requested by the licensee, Public Service Company of Colorado.

Spent nuclear fuel from the Fort St. Vrain plant is stored in an NRC-licensed independent dry fuel storage installation located nearby. The plant is in the process of being converted to natural gas, to be finished in 1999. The repowered plant will include the existing steam turbine generator, two new combination natural gas turbine generator/heat recovery steam generators, and two new exhaust stacks. The repowered facility will produce 471 megawatts of power and use 6 billion cubic feet of natural gas annually.

Fort St. Vrain Web Site.